1. Field of the Invention
The present invention relates to a printed circuit board, an optical module, and transmission equipment, and in particular, to reduction of crosstalk in a transmission line formed in a printed circuit board.
2. Description of the Related Art
A transmission line is formed in a printed circuit board, and an electronic signal (for example, a serial data signal) is transmitted through the transmission line. In the case where a plurality of transmission lines are disposed close to each other in a printed circuit board, deterioration in waveform quality of an electronic signal due to crosstalk is concerned. Crosstalk between transmission lines includes two types, namely, far-end crosstalk (FEXT (Far End Crosstalk), or Forward Crosstalk) and near-end crosstalk (NEXT: Near End Crosstalk, or Backward Crosstalk).
In the case where a plurality of transmission lines are disposed such that parts thereof are positioned close to and in parallel to each other, crosstalk increases when the parts are longer. Further, crosstalk increases with speeding up of an electronic signal (for example, as increase of the bit rate of a serial data signal).